FIELD OF THE INVENTION
The subject of the present invention is a process and a device for diagnosing an ignition system of an internal combustion engine, more particularly adapted to the diagnosis of ignition systems having multiple coils.
The prior art discloses numerous devices for the diagnosis of ignition systems able to diagnose a short circuit or an open circuit of a primary circuit of a coil. Those devices generally consist of an apparatus for measuring a current flowing through the primary circuit of the coil and through an associated switch, as well as a device, generally analog, for comparing the current with a reference value. However, those devices are not suitable when multiple coils have to be controlled at least partially simultaneously. It is then necessary to employ one diagnostic device per ignition coil so that the current flowing through another coil should not disturb a previous current measurement. Moreover, those diagnostic devices need to be matched accurately to the characteristics of the coil to be monitored and have to be matched as a function of the variations in those characteristics, due either to manufacturing scatter, or to variations in operating conditions.